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RE: Through-Bolting of Hollow Unreinforced CMU

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I have seen your situation in the real world, never seen any tests or reports.  When evaluating this condition, I have treated the bolt as a cantilevered beam.  The back face shell and the front face shell are supports which you evaluate for bearing forces.  This usually gives a result of several hundred pounds capacity - not much.
 
Jake Watson, P.E.
Salt Lake City, UT
-----Original Message-----
From: Robert C. Rogers [mailto:rcr(--nospam--at)ssastructural.com]
Sent: Thursday, October 28, 2004 6:06 AM
To: seaint(--nospam--at)seaint.org
Subject: Through-Bolting of Hollow Unreinforced CMU

A question for my colleagues….

 

Anyone out there ever seen an analytical technique in published literature to evaluate the shear capacity of threaded rod through hollow CMU  (i.e., through-bolt) ?  I know that several fastener companies (Hilti, Simspon, etc.) have ICBO test reports showing embedded anchors (with screen tubes in hollow CMU)……but that’s not what I’m interested in……I’ve seen so many “through-bolt” applications with just plain all-thread and some drilled holes but have not seen an analytical approach (perhaps NCMA Tek 12-3a is as close as it gets ?)…..seems like to me there are several limits states….local crushing of CMU at all-thread (i.e., bearing failure)….shear failure of the CMU face shell….bolt shear…. Etc.

 

Any thoughts ?

 

Thanks

Robert C. Roger, P.E.